Heat transfer by infrared radiation
When you pass by a hot object on a cold winter's day - perhaps a hot radiator - and you feel that warm glow, what you're experiencing is a type of electromagnetic radiation called infrared radiation which is one of the ways that heat can travel from one place to another.
Infrared waves can travel through an empty vacuum such as space, so these electromagnetic waves do not need any material (called a 'medium') to travel through, unlike e.g. water waves or sound waves.
All objects emit and absorb infrared radiation. The hotter the object, the more infrared rays are given off each second.
Visible light, infrared and ultraviolet waves are emitted by the sun, travel through the vacuum of space and penetrate the Earth's atmosphere.
Infrared is invisible but can be detected by a thermometer beyond the red end of the 'rainbow' spectrum produced when a beam of white light is dispersed (split up) by a glass prism.
GCSE Physics keywords: Heat, Infrared radiation/waves, Vacuum, Absorb, Emit